1. Field of the Invention
The present invention relates to a clutch drum to be used in a hydraulic clutch for an automatic transmission or the like, as well as to an apparatus for manufacturing the same.
2. Description of Related Art
In order to detect the rotational speed of a clutch drum, there has hitherto been known an arrangement in which a ring-like pulsing gear formed by fine blanking is mounted on, or fitted onto, an external surface of a drum main body and is then welded thereto, and in which pulse signals are generated by a rotation sensor which is disposed opposite to the gear whenever each tooth crest of the gear (or top of each tooth) passes through the rotation sensor.
Further, though a clutch drum is normally made of a cast product, there has recently been developed, for reducing the weight, a metallic plate clutch drum which is made up by pressing spline teeth for engaging with clutch plates on a clutch main body which is obtained by drawing or reducing a relatively thin metallic plate into a cup shape.
However, if the clutch drum is provided with a pulsing gear as described above, the number of parts increases and the mounting of the pulsing gear on the clutch drum is time-consuming, resulting in a higher cost.
In the above-described metallic plate clutch drum the tooth profile can be simply formed by pressing on the drum main body at a high precision. Taking note of this fact, the present invention has an object of providing a low-cost clutch drum having integrally formed thereon pulsing teeth as well as an apparatus for manufacturing the clutch drum.